The invention relates to a device for mass storage of information, and also to a method of storing information with the help of said device.
Numerous techniques are known in the prior art for mass storage of information. Amongst the techniques in most widespread use, mention can be made of non-volatile semiconductor memories, magnetic tapes or disks, and optical disks.
Present-day (magnetic) hard disks present storage density of the order of 100 gigabits per square inch (Gbit/in2) where 1 Gbit=109 bits. Higher densities (up to 400 Gbit/in2) can be achieved in the laboratory with the help of the perpendicular magnetic recording technique. Conventional optical disks present lower recording densities, with the exception of holographic disks, but they are still at an experimental stage, and in any event they are not rewritable.
The techniques that appear to be the most promising for obtaining ultrahigh information storage densities, of the order of 1 terabit per square inch (Tbit/int) or more, where:1 Tbit=103×Gbits=1012 bitsare based on using microtips and they are derived from scanning microscope technologies such as atomic force or tunnel effect microscopy. The article by D. Saluel and J. M. Fedeli entitled “L'enregistrement ultra haute densité device micropointes” [Ultrahigh density recording with microtips], published in Signaux No. 94, September 1999, pp. 9 to 22, summarizes those techniques that are based on principles as varied as storing charge, changing phase, and magnetic recording.